Incidence and risk factors for Psychiatric disorders across Different Health Insurance Systems in Japan


■ 学会名

■ 発表日

■ 筆頭演者
Kosuke Iwasaki
Milliman, Inc., Tokyo, Japan

■ 共同演者
Chise Ha¹, Tomomi Takeshima¹, Yumi Sato², Ikumi Nishi², Shinzo Hiroi², Takumi Sugiyama³, Gen Terashima³, Akiko Hatakama⁴, Ataru Igarashi⁵,⁶
1 )Milliman, Inc., Tokyo, Japan
2 )Shionogi & Co., Ltd., Tokyo, Japan
3 )JMDC Inc, Tokyo, Japan
4 )DeSC Healthcare, Tokyo, Japan
5 )The University of Tokyo, Tokyo, Japan.
6 )Yokohama City University, Kanagawa, Japan.

■ 発表形態

■ 要旨
Japan adopts compulsory healthcare system mainly consisting of employee-based health insurance (EHI) for company employees and their families and the citizens’ health insurance (NHI) for non-/self-employed workers. Our previous study suggested that higher medical costs in NHI patients for mental diseases were attributable to more frequent long-term hospitalization for schizophrenia and depression. In this study, we examined the correlation between insurance type and those diseases.

JMDC database covering EHI data and DeSC database covering EHI and NHI data for 2020 were analyzed. For schizophrenia and depression, age- and gender-specific annual incidences were calculated. Logistic regression was performed for people having health checkup data using sex, age, Charlson Comorbidity Index (CCI), laboratory test results and type of insurance as explanatory variables for incidence of those diseases.

In 2020, target population included 14,422,753 men and 15,120,873 women in NHI while 43,751,233 men and 35,743,604 women in EHI. Age- and gender- specific annual incidences of schizophrenia were higher for NHI compared to EHI in all strata, (e.g., 0.43% vs 0.15% among men aged 40-44) while incidences of depression were not different between NHI and EHI over all the strata. (e.g., 0.65% vs 0.68%). Some explanatory factors had significant odds ratios in logistic regression for schizophrenia, notably 1.91, 0.74, 0.67, 0.50, and 0.58 for CCI, daily drinking, adequate sleep, EHI employee vs NHI and EHI family vs NHI, respectively. For depression, odds ratio was higher for CCI (1.70) and many of the explanatory factors were significant including adequate sleep, EHI-employee, and EHI-family (0.61, 0.91 and 0.80, respectively).

Higher incidence of schizophrenia implied higher vulnerability of population in NHI to the disease. Logistic regression analysis results suggested that population in EHI have lower risk of schizophrenia and depression, although influence of insurance type on depression did not seem remarkable.